/***
 * Copyright 2002-2010 jamod development team
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 * Original implementation by jamod development team.
 * This file modified by Charles Hache <chache@brood.ca>
 ***/

package net.wimpi.modbus.io;

import java.io.EOFException;
import java.io.IOException;
import java.io.DataInput;

/**
 * Interface implementing a non word data handler for the read/write multiple
 * register commands (class 0).
 * 
 * @author Dieter Wimberger
 * @version @version@ (@date@)
 */
public interface NonWordDataHandler {

	/**
	 * Returns the intermediate raw non-word data.
	 * 
	 * @return the raw data as <tt>byte[]</tt>.
	 */
	public byte[] getData();

	/**
	 * Reads the non-word raw data based on an arbitrary implemented structure.
	 * 
	 * @param in
	 *            the <tt>DataInput</tt> to read from.
	 * @param reference
	 *            to specify the offset as <tt>int</tt>.
	 * @param count
	 *            to sepcify the amount of bytes as <tt>int</tt>.
	 * 
	 * @throws IOException
	 *             if I/O fails.
	 * @throws EOFException
	 *             if the stream ends before all data is read.
	 */
	public void readData(DataInput in, int reference, int count)
			throws IOException, EOFException;

	/**
	 * Returns the word count of the data. Note that this should be the length
	 * of the byte array divided by two.
	 * 
	 * @return the number of words the data consists of.
	 */
	public int getWordCount();

	/**
	 * Commits the data if it has been read into an intermediate repository.
	 * This method is called by a <tt>WriteMultipleRegistersRequest</tt>
	 * instance when finished with reading, for creating a response.
	 * 
	 * @return -1 if the commit was successful, a Modbus exception code valid
	 *         for the read/write multiple registers commands otherwise.
	 */
	public int commitUpdate();

	/**
	 * Prepares the raw data, putting it together from a backing data store.
	 * This method is called by a <tt>ReadMultipleRegistersRequest</tt> instance
	 * when finshed with reading, for creating a response.
	 * 
	 * @param reference
	 *            to specify the offset as <tt>int</tt>.
	 * @param count
	 *            to sepcify the amount of bytes as <tt>int</tt>.
	 */
	public void prepareData(int reference, int count);

}// NonWordDataHandler
